1. Field of the Invention
The present invention relates to an array substrate of a liquid crystal display and a repair method thereof, and more particular, to an array substrate of the liquid crystal display device and a repair method thereof that repairs line defects.
2. Description of the Prior Art
Nowadays, because of many advantages, such as high display quality, good space utilization, low power consumption, and low radiation, the liquid crystal display device has become more and more popular. As the liquid crystal display technology advances, the liquid crystal display device has been widely employed in many fields. Generally, the liquid crystal display device includes an array substrate, a counter substrate and a liquid crystal layer sandwiched between the two substrates. The array substrate mainly includes a substrate, pixel structures arranged on the substrate in an array, a plurality of scan lines and a plurality of data lines. Each of the above mentioned pixel structures mainly includes a thin film transistor (TFT), a pixel electrode and a common line. Through generating an electric field between the two substrates, the liquid crystal layer sandwiched between the two substrates is driven by an electric field, and the rotation angle of the liquid crystal is altered to implement brightness control of the display panel.
It is to be noted that, in actual manufacturing, line defects often occur in the array substrate due to process unsteadiness or other factors, the line defects often refer to the defects of the scan lines or the defects of the data lines on the substrate. In order to improve the yield of the liquid crystal display device as well as to reduce the manufacturing cost, the line defects must be repaired. When the line defects reduce the quality of the display, the low quality substrates of the display are scrapped. Therefore, a repair method must be provided to improve the display quality, and to minimize the scrap rate of the substrates. The passages below describe the repairing of data lines with defects and scan lines with defects by conventional methods.
FIG. 1 is a schematic diagram illustrating a repair of a data line in accordance with a conventional laser repair method. As illustrated in FIG. 1, a scan line 11 and a data line 12 are perpendicularly intersected with one another to define a pixel region, wherein the data line 12 includes a plurality of protrusions 21. A pixel electrode 13, which is made of indium tin oxide (ITO), is disposed in the pixel region, and the pixel electrode 13 is electrically connected to the scan line 11 and the data line 12 respectively through a thin film transistor 14. A shielding wire 20 is disposed between the pixel electrode 13 and the data line 12, and the shielding wire 20 is disposed parallel to the data line 12 and overlapping the protrusions 21 of the data line 12. When a line defect occurs at the data line 12, a laser repair method is performed to connect the protrusion 21 to the shielding wire 20, so that the data signals can bypass the broken data line 12, and continue the transmission via the shielding wire 20, improving the yield of the panel. Although the method above can repair the line defects, the laser repair method requires additional structure designs (e.g. the designs of the protrusions 21), which greatly increases the complexity of the pixel structure as well as the difficulty of the process of manufacturing. Furthermore, other defects may be introduced during the method described above, e.g. contamination of the pixel electrode during the formation of the protrusions could occur, affecting the quality of the display of the panel.
FIG. 2 is a schematic diagram illustrating a repair of a data line in accordance with another conventional laser repair method. As illustrated in FIG. 2, a scan line 11 and a data line 12 are perpendicularly intersected with each other to define a pixel region. A pixel electrode 13, which is made of ITO, is disposed in the pixel region, and the pixel electrode 13 is electrically connected to the scan line 11 and the data line 12 respectively via a thin film transistor 14. A common line 15 is disposed in the peripheral region of the pixel electrode 13, and the common line 15 is disposed parallel to the scan line 11 or the data line 12, wherein a portion of the common line 15 disposed parallel to the data line 12 includes a opening part 51. The opening part 51 divides the common line 15 into two sections, and an extension part 16 of the common line 15 partially overlaps the data line 12. When a line defect occurs at the data line 12, the overlapping region between the extension part 16 and the data line 12 are connected by a laser repair method, so that the data signals can bypass the broken data line 12 and complete the transmission via the common line 15, improving the yield of the panel. Although such method is less complicated, the extension part 16 would generate a parasitic capacitance, which adversely affects the display quality.
FIG. 3A is a schematic diagram illustrating a repair of a scan line in accordance with another conventional laser repair method. As illustrated in FIG. 3A, a scan line 11 and a data line 12 are perpendicularly intersected to define a pixel region. A pixel electrode 13, which is made of ITO, is disposed in the pixel region, and the pixel electrode 13 is electrically connected to the scan line 11 and the data line 12 respectively via a thin film transistor 14. When a line defect A occurs at the scan line 11 between two adjacent data lines 12, the repair method includes: first, dividing the pixel electrode 13 above the line defect A into a display portion 13a and a repair portion 13b surrounded by the display portion 13a so that the display portion 13a and the repair portion 13b are electrically insulated from each other; and then electrically connecting the repair portion 13b and the two ends of the broken scan line 11 with the line defect A via a laser repair method. Although such method can repair the scan line with the line defect, the aperture ratio of the display region is reduced, and therefore the display quality is adversely affected. Furthermore, since there are two layers existing between the pixel electrode and the scan line, the level of difficulties when connecting the pixel electrode with the scan line is increased. Consequently, the success rate of the repair is reduced.
FIG. 3B is a schematic diagram illustrating a repair of a scan line in accordance with another conventional laser repair method. As illustrated in FIG. 3B, a scan line 11 and a data line 12 are perpendicularly intersected to define a pixel region. A pixel electrode 13, which is made of ITO, is disposed in the pixel region, and the pixel electrode 13 is electrically connected to the scan line 11 and the data line 12 respectively via a thin film transistor 14. When a line defect occurs at the scan line 11 below the data line 12, the repair method includes: first, dividing the pixel electrodes 13 adjacent to the line defect into a display portion 13b and a repair portion 13a, which are electrically insulated with each other; and then depositing a metal film 41 on the repair portions 13a between the two adjacent pixel electrodes 13 so that two ends of the broken scan line 11 are electrically connected via the metal film 41. Although such method can repair the line defects, the procedures of the repair are more complicated. Also, when depositing the metal film 41, the deposition could be very time consuming and the results of the deposition cannot be guaranteed. Furthermore, the pixel electrode may be contaminated during the deposition process, which adversely affects the display quality.
In summary, the repair method in the prior art in repairing the line defects at data lines cannot achieve a good repair result. If the repair method is employed, the complexity of the pixel structure would increase, the corresponding manufacturing process would be more difficult, and the pixel electrode could be contaminated. Therefore, a simple repair method that is not limited by the position of defects is desired, and thus the present invention provides a rather simple and effective laser repair method.